diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index d5c8a74..62a92b5 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -12,7 +12,7 @@ jobs:
   test:
     strategy:
       matrix:
-        ruby_version: [3.1, 3.2, 3.3, 3.4]
+        ruby_version: [3.1, 3.2, 3.3, 3.4, 4.0]
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
diff --git a/.ruby-version b/.ruby-version
index 47b322c..fcdb2e1 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-3.4.1
+4.0.0
diff --git a/ruby_audit.gemspec b/ruby_audit.gemspec
index d3ebc73..f0a3007 100644
--- a/ruby_audit.gemspec
+++ b/ruby_audit.gemspec
@@ -18,7 +18,7 @@ Gem::Specification.new do |spec|
   spec.homepage      = 'https://github.com/civisanalytics/ruby_audit'
   spec.license       = 'GPL-3.0-or-later'
 
-  spec.required_ruby_version = ['>= 3.1', '< 3.5']
+  spec.required_ruby_version = ['>= 3.1', '< 4.1']
   spec.files         = `git ls-files -z`.split("\x0").reject { |f| f.match(%r{^(test|spec|features)/}) }
   spec.bindir        = 'exe'
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }